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Inappropriate conclusions due to omission of value of statistics

Dear Sir,
It is with interest we read the paper by Simmer et al. where they retrospectively
describe the incidence of cardiac arrest and unexpected deaths in surgical patients
before and after implementation of a rapid response system (RRS). We congratulate
the authors for their effort to describe their experience with the RRS in their hospital.
Unfortunately this paper is apparently subjected to serious bias and incorrect interpretation
of data and statistics, as if statistics do not matter. What the authors found in
fact was the absence of any demonstrable effect of the introduction of a RRS. We are
disappointed that statements as ��Introduction of a RRS resulted in a 50% reduction
of mortality�� have passed the editors and reviewers. A reduction in mortality was
not found at all, as can be derived from the data in the paper and the given Odds
Ratios. The bias of the authors could not be better demonstrated than by their statement
��the positive results were abated by the delayed activation of the medical emergency
team activation�� and ��by the low baseline incidence��. Apparently the believe in
the positive effect of an RRS convinces them that only a type II error can explain
the results without mentioning it as such.

Furthermore, important flaws in and related to the retrospective design are present
in the study. E.g. so-called early warning scores were, as the authors point out not
in use before the introduction of the RRS and therefore not systematically recorded.
This makes an adequate comparison between groups rather difficult. Furthermore, the
definition of ��unexpected death�� can be debated. The authors have defined this as:
��death in the surgical ward or death in the ICU after an unplanned ICU admission��.
Whether death is expected yes or no depends on many factors, among others medical
expertise, how well you look at a patient. Death in a surgical ward can be anticipated
and therefore expected, but according to the authors it is by definition unexpected.
It should be realized that RRS is in fact about detecting patients who are potentially
in the wrong department, the ward instead of the ICU. But not all patients who fulfil
the EWS criteria will benefit from an ICU admission. Finally, what especially worries
us about this paper, that in our view ignores the value of statistics, is the interpretation
of lay people and non-scientist who read the conclusion of this paper. It is of note
that the Dutch Inspectorate has made the introduction of a RRS imperative in Dutch
hospitals, although scientific proof is lacking and it has not been advocated by the
scientific Dutch societies. We therefore plead for a careful representation of data
and we would advice that the conclusion of the paper should be rephrased in: ��Introduction
of an RRS did not result in a reduction in cardiac arrest rates and/or unexpected
deaths. A type II error cannot be excluded��.